Rotary chemical furnace



Ap 9, 1929. L.. Tocco ET AL ROTARY CHEMICAL FURNACB 2 Sheets-Sheet Filed June 22, 1926 April 9, 1929- L. rocco Er AL 1,708,526

ROTARY CHEMICAL FURNACB Fi1e d June 22, 1926 2 Sheets-Sheet 2 Wwf/gy Patented Apr. 9, 1929.

UNHTED STATES 1,768,526 PATENT operi-lcs. y

LUIGI TOCCO AND MICHELE LANDI, OIE PARIS, FRANCE, ASSIGNORS TO SOCIETE LE FOUR CHIMIQUE ROTATIF (SOCIETE ANONYME FRANCAISE 0]?` PARIS, FRANCE.

ROTARY CHEMICAL FRNACE.I

Application sied June 22, 192e, serial No.'117,874, and ni vitaly J'un 26, 1925. 'f'

Our invention'relates to improv'ements in continuously operating rot-ary chemical 4furnaces ofthe type in which the materials to be treated are moved through the various stages of the furnace by the action of gravity.

One of the objects of the invention is to provide a furnace of the character indicated which shall be capable lof general use in the chemical industry for producing va transformation of complex ores or minerals, such as metals, metalloids and their combinations in a continuous cycle` Our invention also contemplates the treatment' of other chemical substances in ay continuous cycle even where the reactions produced involve conditions differing considerably from one another.

Another object of the invention is to provide an improved electric heating arrangement for the furnace. 7,

Still another object of the invention is to provide means for utilizing the excess heat generated by the various reactions for producing energy in the form of steam` whereby the fuel consumption is partially compensa-ted for. 1

Our invention is further comprised in certain novel forms, construction, and combi'- nation of parts, the objects of which are lo provide reliable devices for the purposes stated and to cheapen the cost of manufaclure b vsimplifying the construction'all of which will hereinafter be fully described and claimed.

Other objects of the invention will be obvious to those skilled in the art with reference to the accompanying drawing forming part of this specification, and in Which- Fig. 1 is a. fragmentary sectional view of the furnace;

Fig-2 is an end view of the furnace with parts broken away showing certain details; and

Fig. 3 is a detail partly in section showing pinion i meshes with 'a' toothed ring 8 mounted on'the rotatable cylindricalv body 'ofA the 'furnace I'th'erebyv insuring `synchronous driving of 'the lfeeding mechanism and the automatic regulation of the feeding of the materials to be introduced intolthe furnace. f

Leading from the distributer 4'is'la'tu'be 9 whichconne'cts with a vseconddistributer 1'0. The'said 1distributer loisconnected to the interior'of'the furnace I byrrieans of. a tube 11 through'which the materials'fall into the first zone-Lof the'furnace The furnace'I rotates about'a fixed head A'which is mounted ori'fay support-ing base 15. Mounted on said'head are a pair of brackets 13 and ,14 carrying the feeding and distributi'ng 'apparatus above described.

A pair of armoured conduits 17 extend through said head for-a purpose to be subsequently pointed out Iand are fastened thereto'by meansof clampingnuts 16. A hermetic closing ring 18`is disposed between thel rotary portionf2() and the'fixed head A for preventing the escape of 'gas and vapors. The cylindrical portion 20 of' the' furnace is faced with a metal disc 19'an'd is 'lined' with' a refractory material 21. An aspirator 22 having abell at its evtremit'ypro-` jects through the head A into the zone or chamber L' for the 'purpose of drawing ofi the water' vaporgiven off by the materials while passing through'the said chamber during the4 drying thereof.`

The rotary portion 20 of theffurn'ace I is guided laterall by means of a number of set-s of rollers 25 (Fig. 2) and longitudinally by means of rollers 25 mounted on supports 26. Each of the said rollers 25 bears against an iron ring '23 mount-ed on an expansible' support 24 carriedby the cylindrical element20.

The end of the first zone Ir terminates in a diaphragm 27 arranged to allow the maarranged to allow a passageway 36 between said zone and a third zone Iy on the opposite side of diaphragm 37.

One of the pipes 17, above mentioned, cX- tends 'clear through the furnace and is provided"'with ascrew conveyor 35 for introducing pulverized carbon into the. end of the second zone. T he carbon falls into the diaphragm 37 and mixes with the materials as they pass through the passage way 36 from .the second to the third zone.

The tube 17 containing conveyor 35 projects through the fixed head A'and is providedat tits extremity with a 'charging hopperf38. The shaft of the screw conveyor 35 projects through its tube 17and is coupled to a suitable driving mechanism shown diagrammaticallyatt). l

The second of the tubes 17 contains an air pipe llQ- provided `with a blast nozzle 42 projecting into the Zone I, for supplying air thereto. Carried by the samepipe is a pyromet-erv 41 for checking the temperature.

In the wall of the rotary member 20 adjacent the zone I, are .provided a plurality of heatingresistances. 43 mounted in crevices 44 provided in Kthe said wall. The said resistanccs are ordinaryele'trical heating elements and are protectedfrom oxidation and insulated by means of oxide of zirconium tamped into the said crevices in such a manner as to completely surround the vsaid resistances. Resistances 43 .are supplied .with current byrmeans of apluralit-y of copper collector rings 46 mounted on the rotary ele-` ment4 20 of the furnace by means .of supports i 47, as shown in Fig. l.

Arranged to-bear on thesaid rings are a pluralitypf brushes 48 (Fig. 2) veach receivlng current by means of a cablefl connected thereto. Contact is mader .between the re.- sistances43 and the rings 4G by means. of a plurality o f conductors 55. 4

The zone I, terminates in a fixedhead A similar to the head A about whichA the meniber 20 rotates. `Extending through said head is an aspirator tube 56 opening into the reaction chamber I, for recovering the gaseousproducts of combustion. The eX- tremity ofmember 20 is provided with a facing 19 anda cooperating hermetic sealing ring 18 similar to the corresponding elements previously described with respect to the opposite end of the section I of the furnace.

So far the description has been limited tothe said section 1. Beneath said upper section is disposed a second inclined lfurnace section I2 in which further reaction of-the materials being treated takes place.

A conduit 57 communicates with the chamber Iy of the upper section I through the fixed head A. The conduit 57 is provided in its lowermost side with a grid 58 and a collecting chamber 59 disposed there beneath. Communicatinggwith the chamber 59v is a discharge tube 60. The lead for eX- Yample .contained in the complex ore undergoing treatment fallsinto the chamber 59 -and is d raivn o ffthrough thetube 6 0. The material `remaining' on t-he surface of the grid is adapted to fall through a continuation 61 of conduit 57 surrounded by a water jacket v61 througl'rwhich Wateris circulated through the pipes 62, 63. The extension 61 communicates with `a water-cooled device for separating .the iron oxide of the material undergoing treatment shown diagrammatically at 64 and provided with a -water jacket 65 fe7d by meansof water circulating pipes 66, 6 i

Q vThe lower section .I2 above mentioned is in general similar, to that oisection Il previouslyy described., The drivingl mechanism, the guiding rollersandthe arrangement of the. heatingi elements and their cooperating partsis identical with that described .in connection. with v the upper sectionI and since thesel elements havee been .given the same charactersof reference they need lno further comment. The y,said loiver section I2, however, is divided into two reaction chambers O and Q Whose Walls are independently rotatable abouta ixedhead common thereto which will be.subsequentlydescribed more in detail.

The separating device 64 communicates withthegchamber ,()of Athe section IJ by means of a pipo69 passing through awatercooled head Ai forming a tight joint with the furnace wall 73,oftrefractory material by means of a hermetic ringv'Oanda facing ring 71 similar to the arrangementpreviously described. v Y

Disposed vvithifnv the chamber O is an ordinary multitubular boiler shown diagrammatically at O (Figs. 1 and) having an extremity projecting through the head A., andprovided with a steam collecting pipe 74 and a Water feed'pip'e 75. Extending through the head A.2 are also an aspirator tube 76 lfor drawing ofi' sulphurous acid and an airinletpipe 77 Vboth communicating with the 'chamber O. i i

The rotary elementl 73 is'faced with a plate 79 hermetica'llyr sealed means of a ring 79 .to a. vfixed water-cooled head 80. Fixed to ,said head is 'ay support, 7 8 upon which is carried the inner end of the boilei` O'.

'The material isl adaptedto pass through a. seriesof openings 83 ina triturating device shown diagrammatically at 84, 85 carried by said head 80. fSaidt-riturating device communicates with a conduit 86 through which pulverizedfcarbo'n is injected into the material passi'ng'therethrough. The triturating deviceE is operated by a shaft 88 driving a pinion 89 connected 4tosaid device.

The fixed head is ef'eellulafr structure as shown at 90 is adapted tohave a coolilng fluid circulated therethrough. Said head is also provided with an air inlet pipe 92 provided at its extremity with a blast nozzle 93 opening into the chamber Q. (Fig. 1).

The cylindrical rotatable wall surrounding the chamber Q is'fastencd to the head 80 in precisely the same manner as member 73. 'Ihe lower end of said wall is faced by a plate 97 and rotates about a water-cooled head 97, a. hermetic ring 98 being interposed as previously described.

The lower end of the fixed head 97 is provided with a discharge opening 100 opening into a conduit 99 communicating with a conveyor 101. Associated withsaid conveyor is a hot air aspirator pipe 102; Projecting through the head 97 and communicating with chamber 'Q is an aspirator tube 103 for dra-wing o zinc vapors.

In operation the mineral to be treated is triturated and mixed with a flux in the proper proportions and introduced into the hopper 1. The distributing mechanism associated with said hopper assures an automatic feeding of the said material into the furnace since it is driven by the rotating member ofthe furnace.

The diameter of the upper and lower sec-- tions of the furnace, their inclination, the length of each reaction chamber and the speed of rot-ation are so chosen that the mineral undergoing treatment Will be retained inieach zone fora period of time necessary to produce the required reaction. The inclination of each section of the furnace and their movement keeps the mineral. constantly in motion which movement is-aided by the inertia of the material and thereby exposes all the surfaces of the particles of material undergoing treatment to `cach successive reaction.

The temperature of the first zone Ir is maintained in the neighborhood of 150 C. inothinrrmore taking place in this zone than the driving off of the moisture in the mineral through the suction pipe 22.

The. mineral is then moved into the sccond zone Ix where air is added through the blast pipe 42. The temperature of the second zone is maintained at about 380 C. and an endothermic reaction is produced such as, for example:

The materia-l undergoingr treatment then passes into the third zone Iy, carbon being added as it.pa.sses by the diaphragm 37. The temperature of this zone is maintained at about 500 C. and a second endothern'iic reaction takes place which according to our example is:

PbO CIPb CO The carbon monoxide is drawn off through the. pipe 56 and thelead iscollected in the colleetor59 alreadymentioned. s

. It will be.V noticed .that once the .furnace is in operation itis aneasy matter'to regulate the temperature ofthe whole-'three zones by cutting out or adding. electrical resistanccs 43 whichedue totheir successive disposition permits of a lgradual increase.

in tcmperz-.ture inthe third zoneifrdesircd by `using resistances" of differenti heating characteristics z.1: Y 1 l' The mineral remaining on fthevgrid 58 passes through the separator-64 of .thefelectro-imignctic type which is tool well'known in the .art .to require a detailed .explanation as the .particulartype-forms tno important partv of this inventions-In sthe; said sepa'- ratoriron in the forml'of .(FexQ) .is recovered from the mineral undergoing treatment. 3. -.;f. f,- :1;

The material remaining .finthe separator is led into theffourth zone; Ofinnthe lower section of the furnace. `which-isamaintained at 4about 600 C.I Here;anexothermiereaction takes place which might be for example:

In this zone a complete roasting-of the blend takes place and airis introduced'through the pipe 77 for producing` a transformation into oxide in order .to liberate tlie=SO2.which is drawn out as fast as it-,is given ofi'4 through the 'pipe 76. The 1recuperating..boiler O disposedA in this zonegnotionly permits the temperature of the zone.v to be'regulatedbut also affords a. means of, recovering the excess hea-t of the reaction; lhis boilerfis preferably covered with a refractory envelope (not shown) for protecting itv from the SO2 fumes. The purpose'of the head 80 is to prevent the- SO2 from .beingdrawn into the fifth zone Q, .The triturating device 84, 85 carried thereby is destined to vprevent agglomeration of the mineral passing into zone Q and to .regulate the quantity thereof passingr through. During.thel passing of the said mineral into the zonaQ, the'proper amount of carbon ,is addedfthrough the pipe 86. i

In the fifth and last zonefQthegmaterial passing therein is subjected 5to atemperature of about`1400 C. .whichislmaintained and regulated by means of the resistances 43 similar to those in the third zone Iy. The rcartions which take place, according to the example chosen are as follows:

Zn (vapor) -i- 0 Zn() (volatile) (exothermic) ZnO -l- C Zn (vapor) CO (endothermic) Air is introduced into this zone through the pipe 92 for producing oxidation of the zinc vapors as given in the above'formulae. The zinc vapors are led ofi through the pipe 103 and the CO is separated therefrom by any of the apparatus Well known in the art. The

steam. If the said residue contains a sufiicient quantity of Ca() and Mg() it may be hydrated with water and utilized for building blocks as is well known in theart.

lHaving thus described our invention what we claim as new and desire to secure by Letters Patent is 1.y In a continuous operating rotary furnace ofthe character described, having :two fixed heads,a rotatable element disposed between said heads Iand means associated with said heads for introducing and withdrawing the materials to be treated, the combination of auxiliary apparatus and means driven by said rotary furnace for automatically operating said auxiliary apparatus in accord ance wlth the speed at which 'saidrotary furnace is driven. Y

2. A continuous operating rotary chemical furnace having two fixed heads,'means carried by said heads for taking off the gases of reaction formed at different points remote from said heads and means for introducing the materials to be treated at predetermined points in said furnace as desired.

3. In acontinuous operating rotary chemical furnace, two fixed heads disposed at the ends of said furnace and a plurality of fixed diaphragms disposed in'the interior of said furnace for dlviding it into several reaction chambers carried byV said. heads.

4. In a continuous operating rotary chem ical furnace, two fixed heads disposed at the ends of said furnace and a stationary boiler carried by said heads for recovering excess heat vand cooling the said furnace during operation thereof.

5. In a continuous operating rotary chemical furnace, two fixed heads disposed at the ends of said furnace, a rotatable element disposed between said heads, a plurality of electrical resistances disposed in the interior of said rotatable element for heating and maintaining the quantity of heat desired, supports mounted on the periphery of said rotatable element, a plurality of insulated contact rings mounted on said supports, there being one ring for each of said resi'stances, means for electrically connecting said rings to said resistances, fixed brushes contactingl with said vrings and means for supplying Van electro-motive force to each of said .brushes for the purpose described.

6. In a continuous operating rotary chemical furnace, Vtwo 'fixed heads disposed at the ends of said furnace, rotatable element disposed between said heads, said rotatable clement constituting the wall of the'furnace, a plurality ,ofcre'vces disposed 'on the interior ofsaid wall and `a plurality of electrical resistances disposed.l in said crevices whereby the temperature may be' uniformly regulated to the lextent desired.

7. In a continuous-operating rotary chemical furnace, two fixed heads disposed-vat the ends of said furnace, arotatable element disposed between -said heads, crevices. carried on the interior of said rotatable element',-.a plurality of electricalVresist-ances disposed in said crevices for uniformly regulating the temperature ofthe furnace to the extent del sircd, supports mounted on theperiphery of said rotatable element, a plurality of "insulated contact rings mounted on said supports, there-,being one' ring foreach of said resistances, fixed brushes contacting with said rings iand means for supplying an electric-motive force to each ofsaid brushes-for the purpose described. y f

8. A continuous'operating rotary ical furnace asset forth in claim 7 in which the resistances are `insulated from `the interior ofthe crevices and protected from oxidization by means of'oxide of' zirconium.

9. In a continuous operating rotarych'emical furnace, two fixed heads disposcdrat the ends of said furnace, 'a third -fixed head'disposed intermediate said first mentioned heads for dividing saidv furnace into apl-urality of reaction chambers and a stationary boiler support-ed by one of saidvlirst mentioned'heads and said intermediate head for recovering excess heat and cooling the said furnace during operation thereof.

In witness whereof we aflix our signatures.

I -LUIGI TOCCO.

MICHELE LANDI.

chem- 

